If you already own a licensed version of LOGO! Soft Comfort (e.g., V8.0), you can download the V8.4 Upgrade Package for free.
The Official Siemens Support Site offers a free demo for testing. Full programming, simulation, and archiving. logo soft comfort v8.4 download
Depending on your current status (new user vs. existing owner), there are three main ways to get V8.4: If you already own a licensed version of LOGO